It is known to graft diene rubber particles in an aqueous latex with alkenyl aromatic and alkenyl nitrile monomers to form conventional ABS polyblends.
Such polyblends have used grafted rubber particles ranging from about 0.01 to 0.25 microns to obtain high gloss in formed articles. Polyblends having these small particles have not had high levels of toughness or high elongation at fail. U.S. Pat. No. 3,509,237 has taught that these deficiencies can be overcome by adding up to 30% by weight of grafted large rubber particles, based on total grafted rubber content of polyblend. Said particles having a size of about 0.8 to 2.0 microns or larger.
The use of small and large grafted rubber particles or broad distributions of grafted rubber particles does improve toughness, however, gloss is lowered in proportion to the amounts of large particles used to gain toughness.
It has now been discovered that small diene rubber particles contained in an aqueous latex can be grafted with a particular monomer formulation of alkenyl aromatic, alkenyl nitrile and alkyl acrylate monomers, having 1 to 20% by weight of said alkyl acrylate monomer, to form a terpolymer polyblend having high gloss and toughness. Rubber particles in the range of about 0.01 to 0.50 microns, preferably about 0.1 to 0.25 microns, can be used in the polyblend insuring high gloss in formed articles.